The statements in this section merely provide background information related to the present invention and may not constitute prior art.
Latex products are widely used in a variety of coatings, adhesives, and inks because they offer several benefits, including the ease in which they can be handled and the absence of any substantial amount of volatile organic compounds (VOCs). One specific example of such a latex product is the acrylic latex compositions used in traffic marking paints. Due to the market demand for products that exhibit a shortened setting time, the coating industry has widely adopted coagulation technology for use in latex products. Within the confines of such coagulation technology, protonated polyfunctional amines destabilize the anionically-stabilized latex particles present in the latex products after they are coated onto a substrate. However, in order to retain the stability of the modified latex particles in the latex product prior to application (e.g., during storage), a volatile amine is added to the latex product in order to increase the pH to a level that prevents the protonation of the polyfunctional amine. When the latex product is applied on to a substrate, the volatile amine escapes or evaporates from the applied coating composition. The loss of the volatile amine results in a decrease in the pH of the applied latex coating composition. The decrease in pH triggers the coagulation of the latex particles in the applied coating composition, which results in a faster setting time.
Numerous polyfunctional amine compounds have been utilized as epoxy curing agents and quick-setting additives for latex products. U.S. Pat. No. 6,653,369 describes water dilutable amine curing agents for aqueous epoxy resin dispersions, comprising a combination of an epoxide-amine adduct with an emulsifier. U.S. Pat. No. 5,246,984 describes a water compatible polyamine-epoxy adduct formed by the reaction of a polyamine with a mixture of a monoepoxide and polyepoxides. U.S. Pat. No. 5,804,627 discloses a shelf-stable fast-cure aqueous coating that contains an anionically-stabilized latex, a polyfunctional amine, and a volatile base in an amount sufficient to prevent the protonation of the amine.
Despite their distinct benefit of improving the setting time for a latex product when it is applied as a coating, the use of polyfunctional amine compounds is usually only practical when the pH of the latex product is maintained at 10 or above. When the pH of a latex product is lower than 10, the polyamine tends to destabilize the anionically-stabilized latex particles and form unwanted solids in the latex product. In order to ensure that the pH remains higher than 10 during storage, volatile amines such as ammonia are typically added to the latex product. The need for a volatile amine limits the utilization of these latex products in a wide variety of applications due to the unpleasant odor of the volatile amine and the liberation of an excessive amount of the volatile amine into the environment during use of the latex product.